JPH04170960A - Antibacterial hydroxyapatite - Google Patents

Abstract

PURPOSE:To offer the silver and zinc carrying antibacterial hydroxyapatite which shows safely strong antibacterial power for a long period, heightens a whiteness, and does not cause a change of color by saving it for a long period by allowing hydroxyapatite to absorb and hold water soluble metallic salt of silver and zinc, and thereafter, calcining it. CONSTITUTION:A prescribed quantity of hydroxyapatite is added into a water solution obtained by melting a prescribed quantity of water soluble silver salt and zinc salt, and stirred. After it is stirred enough, a sediment is filtered, washed enough with distilled water, dried, and thereafter, calcined at a prescribed temperature, and thereafter, crushed and target antibacterial hydroxyapatite is obtained. Also, at the time of manufacturing the hydroxypatite by calcium salt and phosphate, water soluble silver salt and zinc salt are allowed to coexist, and thereafter, an obtained sediment is filtered, washed enough with distilled water, dried, and thereafter, calcined by which it is also possible to obtain the hydroxyapatite. The foregoing is desired. As for the zinc quantity allowed to coexist with silver and held, it is necessary that its quantity is at least >=5% by weight against the silver quantity to be held. Also, by executing the calcination at >=961 deg.C being a melting point of silver, the whiteness of powder is further improved.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is an antibacterial hydroxyapatite, specifically a hydroxyapatite supported with silver and zinc, in which the supported metal and/or The present invention relates to antibacterial hydroxyapatite, which can be used in a wide range of applications because it stably maintains white skin for a long period of time without eluting metal ions into water or changing color.

(Prior Art) It has been known for a long time that metals such as silver and zinc and their salts have strong antibacterial and antifungal properties, and various methods have been devised to utilize these. However, when metals and salts are mixed into base materials such as synthetic resins, fibers, and paints, there are problems such as dispersibility in the base materials, elution of metal ions, colorability, and discoloration due to light. , could not be used extensively. In recent years, as a substance utilizing the antibacterial properties of these metals, a substance in which antibacterial metal ions are supported on highly safe ceramics by ion exchange has been proposed. For example, JP-A-60-181002 discloses that antibacterial metal ions are added to zeolite in JP-A-2-180270.
The publication discloses an antibacterial substance in which antibacterial metal ions are supported on hydroxyapatite through ion exchange. These substances can be used relatively safely and widely because the antibacterial metal ions carried thereon are less likely to elute into water and have improved dispersibility into substrates. However, depending on the medium used with these substances, metal ions may be eluted into the medium, so not all media can be used safely.

On the other hand, the eyes are generally sensitive to light and are known to decompose and turn gray or black. Therefore, using silver salt as it is causes discoloration. Although zeolite that has been supported with silver through ion exchange has less discoloration than when silver salt is used as it is, it is inevitable that the color will change over time, and hydroxyapatite that has been supported with silver through ion exchange is Although the discoloration caused by silver is significantly improved compared to zeolite supported with silver,
It cannot be said that discoloration is completely suppressed.

(Problem B to be solved by the invention) In the present invention, antibacterial metals or metal ions do not elute into any medium, so there is no need to consider drug damage caused by metal ions, and they are stable against heat. Because a relatively large amount of antibacterial metals and/or metal ions are adsorbed and retained, silver and zinc support exhibits strong antibacterial activity safely over a long period of time, and has high whiteness and does not discolor even during long-term storage. It provides antibacterial hydroxyapatite.

(Means and effects for solving the problem) As mentioned above, antibacterial zeolite and hydroxyapatite obtained by supporting silver through ion exchange are highly safe.
It is an antibacterial material that is easily dispersed into the base material and is easy to use, but as it slightly discolors over time, special methods are required to preserve it, and prevent deterioration due to discoloration of products using it. I couldn't do anything. Therefore, the present inventors
As a result of investigating a method to produce antibacterial hydroxyapatite that adsorbs and retains silver and exhibits strong antibacterial activity because it adsorbs and retains a large amount of silver, it does not cause silver ion elution or discoloration over time, and has a high degree of whiteness. We were able to obtain antibacterial hydroxyapatite. In other words, when manufacturing silver adsorption-retaining antibacterial hydroxyapatite, the silver and zinc adsorption-retaining hydroxyapatite obtained by treating it with zinc coexisting is fired at high temperature, so that silver and zinc do not elute and the white color is obtained. It was recognized that antibacterial hydroxyapatite with high adsorption and retention of silver that does not discolor over time can be obtained. That is, a predetermined amount of hydroxyapatite is added to an aqueous solution containing predetermined amounts of water-soluble silver salts and zinc salts, and the mixture is stirred. After thorough stirring, the precipitate is filtered, thoroughly washed with distilled water, dried, fired at a predetermined temperature, and then crushed to obtain the desired antibacterial hydroxyapatite. In addition, when producing hydroxyapatite from calcium salt and phosphorus M salt by a conventional method, the precipitate obtained after coexisting with water-soluble silver salt and zinc salt is filtered, washed well with distilled water, dried, and then calcined. Antibacterial hydroxyapatite can also be obtained by this method. Hydroxyapatite is Ca. The synthesis of hydroxyapatite, which has the composition (po,) 6 (OH) 2 and has a stoichiometric molar ratio of Ca/P=''/6, is synthesized from calcium salt and phosphate. However, calcium phosphate salt having a molar ratio of Ca/P = 1.4 to 1.8 and having properties similar to hydroxyapatite is also used in the antibacterial hydroxyapatite of the present invention in exactly the same way as hydroxyapatite. Therefore, in the present invention, these calcium phosphate salts are also included in hydroxyapatite.

Naturally, the whiteness of the antibacterial hydroxyapatite obtained is affected by the amount of supported silver as well as the adsorption and retention ratio of silver and zinc. That is, in order to obtain antibacterial hydroxyapatite that has high whiteness and does not discolor over time, it is desirable that the amount of silver adsorbed and retained is 20% or less, preferably 15% or less by weight of the hydroxyapatite. Considering antibacterial power, the amount of silver retained is 0.0
It is desired that it is 0.001% or more. The amount of zinc to be retained in coexistence with silver must be at least 5% by weight relative to the amount of silver to be retained, and the amount retained can be arbitrarily selected. The silver and zinc adsorption-retaining hydroxyapatite obtained in this way is
Temperature 800 at which significant crystal growth of roxyapatite begins
The whiteness of the powder is further improved by firing at a temperature of 961'C or higher, more preferably 961'C or higher, which is the melting point of silver.

When antibacterial hydroxyapatite obtained by adsorbing and supporting silver salt in the coexistence of zinc salt is fired at high temperature,
Since crystal growth occurs significantly from around 0.degree. C. and sintering shrinkage occurs, the mutual bond between adsorbed silver, zinc or their ions and hydroxyapatite is strengthened. Furthermore, when it is fired at 961°C or higher, which is the melting point of silver,
The mutual bond between silver, zinc or these ions and hydroxyapatite is further strengthened. Furthermore, as the firing temperature increases, crystallization of antibacterial hydroxyapatite progresses. For these reasons, it is presumed that the higher the firing temperature, the more the adsorbed and supported metals are prevented from eluting into water, the whiteness increases, and discoloration is prevented.

EXAMPLES The present invention will be specifically described below with reference to Examples.

Example 1) Add hydroxyapatite 1.1 to 101 distilled water. Okg,
Add 0.005 g of silver nitrate and 455 g of zinc nitrate and stir. Filter the product, wash well with distilled water, dry, and
After firing at 00℃, it is crushed to give 0.0001% silver.
Antibacterial hydroxyapatite carrying 10% zinc was obtained.

Example 2) Hydroxyapatite 1.1 to 101 distilled water. Okg,
Add 32 g of silver nitrate and 28 g of zinc nitrate and stir. Filter the product, wash thoroughly with distilled water, dry, and heat at 1,200°C.
After firing, the product was pulverized to obtain anti-I hydroxyapatite carrying 2% silver and 0.6% zinc (30% by weight relative to silver).

Example 3) Hydroxyapatite 1.0kg in 10A' distilled water
, 64 g of silver nitrate, and 37 g of zinc nitrate were added and stirred. The product was filtered, thoroughly washed with distilled water, dried, and
After firing at ℃, it is crushed to give 4% silver and 0.8% zinc (
Antibacterial hydroxyapatite (20% by weight based on silver) was obtained.

Example 4) Hydroxyapatite 1.1 to 101 distilled water. Okg,
Add 128 g of silver nitrate and 184 g of zinc nitrate and stir.

Filter the product, wash thoroughly with distilled water, dry, and reduce to 1.20
After firing at 0℃, it is crushed to give 8% silver and 4% zinc (w
Antibacterial hydroxyapatite was obtained.

Example 5) 1.0 kg of hydroxyapatite in 1 liter of distilled water,
Add 240 g of silver nitrate and 46 g of zinc nitrate and stir. Filter the product, wash thoroughly with distilled water, dry, and add 20 l.
After firing at 0℃, it is crushed to give 15% silver and 1% zinc (
Antibacterial hydroxyapatite supported with 6.7% by weight of silver was obtained.

Example 6) Hydroxyapatite 1. Okg,
Add 320 g of silver nitrate and 46 g of zinc nitrate and stir. The product was filtered, thoroughly washed with distilled water, dried, and
After firing at °C, the product was crushed to obtain antibacterial hydroxyapatite carrying 20% silver and 1% zinc (5% by weight relative to silver).

Example 7) Metal ion elution test Each sample of Example 1) to Example 6) was added to 100 ml of distilled water, stirred for 30 minutes, and the metal ions in the solution were measured using an atomic absorption spectrophotometer. I asked for the quantity.

As a result, no elution of silver or zinc was observed.

Example 8) Antibacterial activity test 5.6 x 10' of Staphylococcus aureus was added to phosphate buffered saline containing 1% by weight of each of the samples from Examples 1) to 6).
The antibacterial activity against Staphylococcus aureus was measured by adding the bacterial solution containing 1. - As a result, no bacteria were detected within 24 hours.

Example 9) Whiteness Test The whiteness of the antibacterial hydroxyapatite powders prepared in Examples 1) to 6) was measured using a spectrophotometer. Barium sulfate was used as a standard sample. Also, example 6
), 20% silver alone without zinc
Supported antibacterial hydroxyapatite was prepared and its whiteness was measured for comparison.

This result shows the effect of zinc content on whiteness.

Example 10) Antibacterial hydroxyapatite was produced in the same manner as in Example 2) except for the firing temperature. Regarding the firing temperature, 100℃ for drying only, 700℃, 800℃, 900℃, 965℃
°C, 1. Powder X-ray diffraction and whiteness measurements were carried out at eight different temperatures: OO0°C, 1,200°C and 1,250°C. Furthermore, the whiteness after 36 hours of ultraviolet irradiation was also measured. In addition, for comparison, measurements were also made on hydroxyapatite powder that does not support metal, and in the powder X-ray diffraction diagram at 100 ° C to 1,250 ° C.
The peaks seen at 2θ 38.1” and 44.3° (
*) is the peak of silver. All other peaks are hydroxyapatite peaks.

According to the results of whiteness measurement, the whiteness is high and does not discolor over time at temperatures of 800° C. or higher. In this way, the degree of whiteness is high,
In order to obtain silver-supported antibacterial hydroxyapatite that does not discolor over time, the firing temperature should be set at 800° rather than a broad peak at 100°C or 700°C, as seen in these powder X-ray diffraction patterns. It is necessary to have a crystallinity with a sharp peak of C or higher.

(Effect of the invention) The antibacterial hydroxyapatite that adsorbs and retains silver according to the present invention does not elute the retained metal into water, so it is non-toxic, has high whiteness, and does not cause discoloration due to silver, so it can be used in a wide range of applications. have.

[Brief explanation of drawings]

The figure shows the X-ray diffraction patterns of the antibacterial hydroxyapatite obtained at different firing temperatures. Figure 1 is an X-ray diffraction diagram when dried at 100°C. Figure 2 is an X-ray diffraction diagram when fired at 700°C. Figure 3 is an X-ray diffraction diagram when dried at 700°C.
X-ray diffraction diagram when fired at °C Figure 4 is an X-ray diffraction diagram when fired at 900 °C Figure 5 is an X-ray diffraction diagram when fired at 965 °C Figure 6 is an X-ray diffraction diagram when fired at 1000 °C Case X
Line diffraction Figure 7 is an X-ray diffraction diagram when fired at 1200°C, and Figure 8 is an XNIA diffraction diagram when fired at 1250°C. Agent Patent Attorney Hideaki Kuwahara Figure 1 Figure 2 Figure 5 Figure 6

Claims (5)

[Claims] (1) Antibacterial hydroxyapatite characterized by adsorbing and retaining water-soluble metal salts of silver and zinc on hydroxyapatite and then firing. (2) The antibacterial hydroxyapatite according to claim (1), wherein the retained amount of zinc is 5% by weight or more based on the retained amount of silver. (3) The amount of silver retained is 2 compared to hydroxyapatite
Claim (1) or (2) that the amount is 0 to 0.0001% by weight.
Antibacterial hydroxyapatite. (4) The antibacterial hydroxyapatite according to any one of claims (1) to (3), wherein the firing temperature is 800°C or higher. (5) The antibacterial hydroxyapatite according to any one of claims (1) to (3), wherein the firing temperature is 960°C or higher.